Teresa Cruz

Reproductive cycle of Pollicipes pollicipes at Cabo de Sines, south-west coast of Portugal

The reproductive cycle of the pedunculate barnacle Pollicipes pollicipes from two intertidal levels (mid and low) at Cabo de Sines, south-west coast of Portugal has been described. Pollicipes pollicipes larger than 12.5 mm (rostrocarinal distance, RC) are simultaneous hermaphrodites. Minimum size for maturity of the female gonad was 12.5 mm (RC) whilst sperm production is achieved at a smaller size (10 mm). The breeding season was from April to September. Reproductive activity was similar at both tidal levels and was significantly correlated with seawater temperature. Brooding activity was most pronounced in late spring and summer when seawater temperature ranged from 18 to 21°C. Throughout the year, sperm was stored in the seminal vesicles, although the testes regressed from October–December. The female gonad was resting in October–January and active during March–September. During resting, only a few empty ovarioles were observed. At the beginning and in the middle of the reproductive season (March to August), the ovary was completely disrupted after fertilization and ovary recovery occurred simultaneously with egg development. During the end of the reproductive season (September–October), synchrony was retarded as recovery of the ovary was slower than egg development. The pattern of functioning of the female gonad should allow production of several broods during the season.

Loss of thermal refugia near equatorial range limits

This study examines the importance of thermal refugia along the majority of the geographical range of a key intertidal species (Patella vulgata Linnaeus, 1758) on the Atlantic coast of Europe. We asked whether differences between sun-exposed and shaded microhabitats were responsible for differences in physiological stress and ecological performance and examined the availability of refugia near equatorial range limits. Thermal differences between sun-exposed and shaded microhabitats are consistently associated with differences in physiological performance, and the frequency of occurrence of high temperatures is most probably limiting the maximum population densities supported at any given place. Topographical complexity provides thermal refugia throughout most of the distribution range, although towards the equatorial edges the magnitude of the amelioration provided by shaded microhabitats is largely reduced. Importantly, the limiting effects of temperature, rather than being related to latitude, seem to be tightly associated with microsite variability, which therefore is likely to have profound effects on the way local populations (and consequently species) respond to climatic changes.

Growth of Pollicipes Pollicipes (Gmelin, 1790) (Cirripedia, Lepadomorpha) On the Sw Coast of Portugal

Pollicipes pollicipes is widely used as food and is the subject of intensive fisheries in Portugal. Since November 1990 growth of this species was studied on the SW coast of Portugal. Two kinds of methods were used: (1) individual growth: the adjacent substrata were marked with polyester resin and the organisms were mapped and measured (Rostro-Carina length=RC) every month; 2) spatial variability of allometric growth: various biometrical measures were used for animals from different habitats; the relationship between these values and the organic weight were established. The results of these analyses suggest that there are spatial (due to tide and light related factors) and temporal differences (growth rates arc higher in spring and summer) in the growth of this pedunculate barnacle. In this study RC was the biometrical variable that best represented the linear growth of this species and we recommend its use for fishery control purposes.

Settlement patterns of Chthamalus spp. at Praia da Oliveirinha (SW Portugal)

Abstract Recruitment of Chthamalus spp. is intense during spring and summer but the number of settled cypris larvae is very low when compared to the high number of Chthamalus spp. metamorphs. In the summer of 1997 at Praia da Oliveirinha (SW Portugal), two hypotheses were tested: 1) the cypris larvae of Chthamalus spp. metamorphose in one tidal cycle; and 2) the settlement of Chthamalus spp. is higher during diurnal high tide compared with nocturnal high tide. The results indicate that cypris larvae of Chthamalus spp. can metamorphose in one tidal cycle. The hypothesis of higher settlement during diurnal high tide could not be tested at the mid and upper levels of C. montagui distribution due to a significative heterogeneity of variances. At the lower level, the results support this hypothesis. In spite of these data having been collected on a single shore and on a few sampling dates, these results suggest that more studies using different spatial and temporal scales are needed to see if this pattern is general.

Distribution and abundance of co-occurring chthamalid barnacles Chthamalus montagui and Chthamalus stellatus (Crustacea, Cirripedia) on the southwest coast of Portugal

Two co-occurring chthamalid barnacle species occur on the rocky shores of continental Portugal: Chthamalus stellatus (Poli) and Chthamalus montaguiSouthward. In the present study, patterns of distribution and abundance (density and percentage cover), both vertically (tidal level) and horizontally (wave action), were studied for each species on headlands (more wave action) and not on headlands (less wave action) and at two spatial scales (shore and site) and three tidal levels (low, mid and upper). Chthamalus montagui was significantly more abundant than C. stellatus in both degrees of wave action and at all tidal levels. Despite this great difference in abundance and considering each species individually, C. montagui was more abundant at mid tide-level, while C. stellatus was more abundant at the low tide-level, and C. montagui was less abundant on headlands, while C. stellatus was more abundant on headlands. Small-scale variability (between sites, tens of meters) of abundance of each species was detected, while differences on a larger scale (between shores, tens of kilometres) were not significant.

Impact of freshwater inputs on the spatial structure of benthic macroinvertebrate communities in two landlocked coastal lagoons

Landlocked lagoons are naturally stressed environments. They are strongly influenced by freshwater input which not only varies naturally, but which is also impacted by anthropogenic activities. This study investigated the direct influence of freshwater discharges on the distribution patterns and abundance of benthic communities in two neighbouring landlocked coastal lagoons, assessing the whole system and the confluence area of each tributary. Sampling occurred in the wet and dry seasons of 2011 at two distances from freshwater discharge locations. Both lagoons were colonized by species from two different pools, freshwater and marine. Freshwater flow rates had a direct influence on the spatial structure of the benthic communities of brackish-water/freshwater interface areas, where also specific taxa can act as early indicators of freshwater input variations. The intensity of this influence is highly dependent on lagoon size, creating spatial heterogeneity or affecting the entire system. The benthic fauna at the confluence of the tributary that depends almost exclusively on groundwater showed the lowest variability, suggesting that the biogeochemical nature of the groundwater may be a central cause for setting specific ecotones. The results suggest that benthic communities of landlocked coastal lagoons can be highly impacted by flow reduction from freshwater aquifers under drought conditions or water abstraction activities.